Swindler is eccentric and astute (4,5)
I believe the answer is:
card sharp
'swindler' is the definition.
(I know that card sharp is a type of swindler)
'eccentric and astute' is the wordplay.
'eccentric' becomes 'card' (card can mean an eccentric person).
'and' says to put letters next to each other.
'astute' becomes 'sharp' (synonyms).
'card'+'sharp'='CARD-SHARP'
'is' acts as a link.
(Other definitions for card sharp that I've seen before include "Cheat at poker, say" , "manipulating the pack?" , "Cheating gambler" , "one whose hands are not to be trusted" , "You won't get a good deal out of one" .)